The rolling upgrade feature takes advantage of versioned packages.

Package names have the following format:

<HDP-component>_<HDP-version>-<component-package>

For example:

hadoop_2_2_9_0_$BUILD-hdfs

HDP 2.2 components are located at /usr/hdp/<HDP-version>/<HDP-component>. The /usr/hdp/current subdirectory contains links to the active HDP version for each component.